Prospective immunological follow-up in household contacts of Mexican leprosy patients.
A 6-year prospective study of 79 household contacts of leprosy cases was made in order to correlate the development of the disease with their specific T-cell immunity, measured by the Mitsuda test, and levels of anti-Mycobacterium leprae antibodies determined in three consecutive observations with the FLA-ABS test. Overall in the contacts, 71.7% were Mitsuda positive and 93.6% showed seropositivity, without regard to their age, sex, or leprosy type of their index case. Households were divided into lower-risk and higher-risk groups according to either the paucibacillary or multibacillary character of their index case. The lower-risk group consisted of 19 contacts of 2 tuberculoid (TT) and 5 indeterminate cases. The higher-risk group was made up of 60 household contacts of 18 active lepromatous (LL) cases. All but two contacts in the former group had a positive Mitsuda reaction; the most common antibody titer was 1:160, with a tendency to stabilize or decrease over time. In the two Mitsuda-negative contacts, increased antibody levels were observed. In the higher-risk group, 61.6% were Mitsuda positive and showed a humoral profile similar to those Mitsuda positive in the lower-risk group. In most of the Mitsuda-negative LL contacts, the antibody levels remained constant or progressively increased, suggesting a high probability of active subclinical infection. This assumption was partially supported by the finding of a new borderline lepromatous (BL) leprosy case in the Mitsuda-negative LL contact group. Nevertheless, the contribution of the close and extensive contact with a multibacilliferous case as a risk factor was difficult to evaluate because of the small size of the sample studied.
Amezcua
M E
ME
Laboratory for Mycobacterial Research, Instituto Nacional de Diagnóstico y Referencia Epidemiológicos, Secretaría de Salud México.
Escobar-Gutiérrez
A
A
Barba-Rubio
J
J
Cázares
J V
JV
Mayén
E
E
Chávez-Núñez
M
M
Peña
R C
RC
Rodríguez
R
R
Pastén
S
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005190:Family; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007916:Lepromin; D007918:Leprosy / Q000276:immunology / Q000635:transmission*; D015440:Leprosy, Lepromatous / Q000276:immunology / Q000635:transmission; D015441:Leprosy, Tuberculoid / Q000276:immunology / Q000635:transmission; D008297:Male; D008800:Mexico; D008875:Middle Aged; D009166:Mycobacterium leprae / Q000276:immunology*; D011446:Prospective Studies; D012307:Risk Factors
D000907:Antibodies, Bacterial; D007916:Lepromin